Objective To investigate the correlation between left atrial diameter measured by echocardiography and atrial fibrillation（AF）. Methods 45 patients with AF from July 2019 to August 2020 were selected. The left atrial diameter（LAD） was measured by echocardiography. According to the size of left atrial diameter

they were divided into three groups: group Ⅰ LAD≤37 mm

group Ⅱ 38-40 mm

group Ⅲ>40 mm. Results（1）The SV

CO

EF and E/A in group III were lower than those in group Ⅰ and group Ⅱ（p<0.05）;（2）There was no significant difference in SV

CO

EF and E/A between group Ⅰ and group Ⅱ（p>0.05）;（3） LAD in patients with permanent AF was higher than that in patients with paroxysmal AF and persistent AF

and LAD of persistent AF was higher than that of paroxysmal AF（p<0.05）. There was no significant difference in LVEDd

LVESD

IVST and LVPWT among the three types of AF（p>0.05）. Conclusions There is a significant relationship between the size of left atrial diameter measured by echocardiography and atrial fibrillation

and the size of left atrial diameter can show the severity of atrial fibrillation.